Counterbalanced apron for planers and the like



Nov. 14, 1950 J. M. WALTER COUNTERBALANCED APRON FOR PLANERS AND THELIKE Filed Nov. 50, 1946 INVENTOR. rfamv M #490153.

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Patented Nov. 14 1950 l 2,530,343 COUNTERBALANCED APRON FOR PLANERS ANDTHE LIKE John M. Walter, Cincinnati, Ohio, assignor to The G. A. GrayCompany, Cincinnati, Ohio, a corporation of Ohio Application November30, 1946, Serial No. 713,325

7 Claims.

1 My invention relates to aprons, otherwise called clapper blocks suchas are used in metal planers, the function of which is to hold thecutting tools, and further to pivot so as to lift the tools from workingengagement with the material being planed, during the return stroke ofthe bed on' which the material is supported.

The objectof thepresent invention is to pro vide a spring counterbalancefor the apron or clapper block. It is also an object to provide such acounterbalance as will exhibit a minimum of fluctuation in its supportedload throughout the angle to which such an apron is likely to be shiftedduring the'return stroke of the machine.

Aiurther object is to make economical provision for the aboveimprovements, ready adjustability and strong and sturdy construction.

' The particular construction of the tool box (called often-clapper'box)and-the apron, to be usedwith my improvementdoes not have specialimportance. Ihave shown the invention as applied to a construction whichin part at least is shown in my application for letters Patent SerialNo. 653,223, filed March 8, 1946, now Patent No. 2,489,942, granted Nov.29, 1949, but this is essentially for purposes of illustration.

In the drawings:

Figure 1 is a front elevation showing the tool box and apron, with thecounterbalance of my invention applied.

Figure 2 is an end elevation taken from the side of the counterbalancespring.

Figure 3 is an enlarged fragmentary,sectional view taken on the line 33of Figure 2.

The tool box or clapper box of the device is illustrated generally at l,having side walls 2, 2, thus forming a cavity in which the apron 3 orclapper block is mounted by means of a mounting pin to held between thetwo side walls at a position to engage pivotally the upper end of theapron. The apron is shown as a solid block of metal 3 having the toolmounting clamp bars 5 on its outer face, said bars held on studs 6. Asin normal construction, there are shoes secured by suitable rivets tothe face of the apron. The illustrated example shows a normal lower shoe6a, and for the upper shoe shows one indicated at I, which projectslaterally from the apron as at la, for a purpose to be described. As inmy application for letters patent above referred to, the lower end ofthe apron is shown as having a projected lower end 8 which engages in anundercut pocket in the tool box lower edge. It will normally bedesirable to form the mounting pin for the apron with a slight taper,and to bore the top of the apron with a matching hole.

Mounted near the top of one of the side walls there is provided a springpilot piece 9. This piece is located on the axis of the mounting pin forthe apron, and has a head l0 bolted to the side wall of the tool box,with a cavity l I to clear the end of the apron mounting pin. The mainbody of the piece 9 is cylindrical and arranged to support a helicalspring I2. The end 90. of the pilot piece is shown as reduced indiameter and provided with a collar l3.

- The spring [2 has an end In turned at right angles which enters a holein the collar l3, provided for that purpose. There is a radial hole M inthe-collar for insertion of a tool to adjust the position of the collar,and set screws l5, preferably at two locations, serve to hold the collarin adjusted relation'on the end 9a of the pilot piece. I

' The :other end of the spring is projected sufficiently as at 4 to belocated in back of the lateralprojection la of the shoe 1 on the apron.The thickness of the apron with reference to the sidewalls of the toolbox is such that this shoe does not prevent the seating of the apronagainst the face of the pocket formed in the tool box by the two sidewalls and the main body of the box.

It will be noted that the spring tends to raise the apron from its seatin the tool box and thus to counterbalance the weight of the apron whenit is swung outwardly to clear the work on its return stroke. The apronis shown as provided with a tilting device in the form of a sliding pinI! in a sleeve type bolt l6 held in the tool box. When using a liftermechanism it is highly desirable to make it of light construction, andthe use of a counterbalance as now described permits this. No particulartype of lifter'is required, however, and hence I have illustrated only apin, as noted above. Also the use of one of the shoes on the apron as anabutment for the spring, while convenient, is only optional. Any lateralprojection will serve.

A torsional spring such as is used, (in this instance with six turns ona fairly large radius), is long enough so that its action is about thesame with reference to the load on the apron when it is swung out atvarious angles. As is apparent the structure shown could be placed ateach side of the tool box instead of on one side only.

The mounting piece I0 could be omitted and the torsion spring and collarcould be mounted directly on the swivel pin, if the swivel pin werefixed against rotation in the tool box.

If the swivel pin was tight in the apron and free in the tool box, thetorsion spring and collar could then be mounted on the swivel pin andone the mounting piece would not have to be co-axial with the swivelpin, but instead could be mounted at a lower position on the side of thetool box. The position of the mounting piece shown on the drawing waschosen because it puts the spring out of the way where it interferes theleast in normal operation of the machine.

Having thus described my invention, what I having an end abutting thetool box so arranged as to exert energy in the direction of swinging theapron on its pivot to raise the apron from its seat to counterbalancethe weight thereof during a return stroke.

2. The combination of a tool box and an apron pivotally mounted thereon,a mounting piece for a helical spring secured to the tool box, and ahelical spring thereon having an end engaging the apron in a directionto exert the torsional effect of said spring in opposition to the weightof the apron.

3. The combination of claim 2 in which the apron is provided with alateral projection behind which the spring end is in abutment.

4. The combination of claim 2 in which the other end of the spring isretained in a member adjustable in its position on the mounting piece.

5. The combination of claim 2 in which the other end of the spring isinserted into a collar, said collar mounted so as to be adjustablearound 4 the mounting piece, and means for holding the collar inadjusted position.

6. Mounting means for a helical spring on the side of a tool box inplaners, for the purpose described, comprising a mounting piececylindrical as to body to receive a helical spring, having a headsecured to said side, said mounting piece having a reduced cylindricalportion at the end, a collar on said reduced cylindrical portion, saidcollar having a lateral orifice position to receive a right angle bentend of a helical spring when arranged over the body, and means forretaining said collar in adjusted position on said reduced cylindricalportion.

7. In combination a tool box, an apron pivotally mounted at its upperend on the tool box and arranged for the mounting of tools thereon, anda torsional spring engaged as to its helical portion on one of saidparts, and engaged at an end thereof to the other of said parts, saidspring arranged to exert its force to tend to lift the apron from adepending position on the tool box.

JOHN M. WALTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,266,486 Kleinegris May 14, 19181,775,963 McCarroll Sept. 16, 1930 FOREIGN PATENTS Number 7 Country Date498,089 France Dec. 27, 1919

